Georgia Department of Natural Resources / Permit 15488

At least 13 critically endangered North Atlantic right whales died this summer, in what has been described as 'carnage.' The cause of the deaths is unknown, but at least three were struck by ships and one became entangled in fishing gear, reports Erik Stokstad for Science. Today, the US National Oceanic and Atmospheric Administration declared the die-off to be an 'unusual mortality event,' which will trigger an investigation into the deaths.

Why it matters: North Atlantic right whales were nearly hunted to extinction — there were as few as 50 remaining by the turn of the century. Thanks to conservation efforts like moving fishing grounds and shipping lanes, their numbers had recovered to roughly 465 by 2011. Still, this many deaths in one season is "unprecedented," New England Aquarium biologist Moira Brown told Science, "the population can't withstand this."

Climate change? It's unclear why so many whales are dying, but trends show the whales have been following their food further North in recent years, possibly putting them in closer contact with fishing grounds and shipping lanes. Concerns about entanglement caused Canada to close a portion of their snow crab fishery in July.

Go deeper

Post-debate poll finds Biden strong on every major issue

Joe Biden speaks Friday about "The Biden Plan to Beat COVID-19," at The Queen theater in Wilmington, Del. Photo: Drew Angerer/Getty Images

This is one of the bigger signs of trouble for President Trump that we've seen in a poll: Of the final debate's seven topics, Joe Biden won or tied on all seven when viewers in a massive Axios-SurveyMonkey sample were asked who they trusted more to handle the issue.

Why it matters: In a time of unprecedented colliding crises for the nation, the polling considered Biden to be vastly more competent.

Bryan Walsh, author of Future
3 hours ago - Science

The murder hornets are here

A braver man than me holds a speciment of the Asian giant hornet. Photo: Karen Ducey/Getty Images

Entomologists in Washington state on Thursday discovered the first Asian giant hornet nest in the U.S.

Why it matters: You may know this insect species by its nom de guerre: "the murder hornet." While the threat they pose to humans has been overstated, the invading hornets could decimate local honeybee populations if they establish themselves.